So i may be the only one with this particular need, but in case anyone else out there wants to use unpowered mics in the mic port (handle not attached), then you'll need something like this to make it work.

$20 Mic power capsule for any 3.5mm 1/8" Microphones. Solves Canon C100 issue on Vimeo

Watched the video and it was very informative. However....I have recently purchased the C100 and I am shocked to hear that I cannot use my Sennheiser G2 series wireless with the 1/8" mic jack. Are you 100% sure of this? In a pinch I could use the XLR cable from the wireless unit but the 1/8" would be ideal since I wouldn't even need the handle. This seems odd.

seems you confused it a bit. the sennheiser wireless works just fine... if you plug just the lavaliere mic into the port, or any other unpowererd mic, it will not work